Dental structures such as caps, crowns and bridges are bonded to natural tooth roots by conventional cements. It is well known, that the removal of cemented dental structures may be necessary for one or more of the following reasons:
(a) The occurrence of dental decay.
(b) To examine the vitality and pulpal involvement of an underlying tooth.
(c) To repair cemented dental structures made defective by the wear of materials.
(d) The loss of selected supporting teeth.
It is also known that natural tooth roots are connected to bone structure by a matrix of connecting fibers. It is said that the connecting fibers exhibit a resultant vector force which holds the tooth root in place, which vector force operates substantially along a longitudinal axis in the direction of the top to bottom of the tooth. Thus, properly directed impacting forces permit the use of short force magnitude but of high frequency to break or fracture the cement bonds holding the dental structure to the tooth root with a minimal detrimental effect to the fibers or natural tooth roots.
In the prior art, removal of dental structures such as caps, crowns and bridges was achieved by sacrifice of the tooth, or, by application of a rigid grasping means to the structure followed by the manual application of an impacting or leverage force in an attempt to break the cement bonds. However, prior art devices could apply only in exact magnitudes of impacting forces since manual means were used. Such manual means were further limited in that the oral cavity is not large enough to permit easy direct impacting to those dental structures located near the rear of the cavity. Other consequences of the use of prior art apparatus are patient discomfiture, and in convenience to the dentist occasioned by the cumbersome mechanical apparatus.
Some recent progress has been made by the use of diminutive ultrasonic probes for working on teeth to remove orthodontics and other dental structures, such as disclosed in U.S. Pat. Nos. 5,106,302 and 5,320,532 to the Farzin-Nia et al